In a semiconductor manufacturing process, in order to secure a high yield, it is important to find defects generated in the manufacturing process at an early stage and to take countermeasures. A scanning electron microscope (SEM) type defect observation device is a device for observing a defect generated in, for example, a semiconductor manufacturing process, and is a device for observing an image of a defect coordinate detected by a higher-rank defect inspection device with higher image quality than in the higher-rank defect inspection device. The higher-rank defect inspection device is, for example, an optical defect inspection device. Specifically, first, a sample stage is moved to the defect coordinate output from the higher-rank defect inspection device, and a defect which is an observation target is imaged at a low magnification to the extent of being included in a field of view. Next, the defect coordinate is detected from the captured low magnification image, the sample stage is moved so that the defect is located at the center of the field of view, or the imaging center is moved, and a high magnification image for observation at a high magnification suitable for defect observation is acquired. As mentioned above, the reason why a defect coordinate is detected with a low magnification image before a high magnification image for observation is acquired is that a defect coordinate output from a higher-rank defect inspection device includes an error within a range of a device specification, and thus it is necessary to perform a process for correcting the error in order for an SEM type defect observation device to acquire a defect image with high quality.
A process of automatically acquiring such a high quality defect image (high magnification image) is called an automatic defect review or automatic defect redetection (ADR). Accuracy of a coordinate for detecting a defect in a higher-rank defect inspection device, a physical characteristic of an observation target, or the like differs depending on the type of defect which is the observation target. Therefore, in the ADR, it is necessary to optimize acquisition conditions for a low magnification image for detecting a defect or acquisition conditions for a high magnification image for observing the defect, depending on the type of defect which is an observation target. The optimization is required to be performed by taking into consideration a balance between defect detection accuracy and throughput in the ADR. Thus, a plurality of defect detection methods, such as a defect detection method prioritizing improvement of defect detection accuracy or a defect detection method prioritizing improvement of throughput are prepared in the ADR, and are used depending on purposes. As a defect detection method, there are, for example, cell comparison in which adjacent pattern units are compared with each other with respect to repeated patterns in a single image, or die comparison in which an image of an inspection target location is compared by using an image of a position corresponding to an inspection target location in another die as a reference image.
PTL 1 discloses that “a defect is detected in a cell comparison method, then it is determined whether or not a defect is detected in the cell comparison method, and, as a result, in a case where it is determined that a defect cannot be detected in the cell comparison method, transition to a die comparison method in which a defect can be reliably detected occurs”.